if that's the only one they are on then yeah, that is what I would do. They can survive though even if there is some moisture so if you plan on putting that rock back in consider putting it in the over or waiting a long time to be sure they are dead (or soak it in some water with bleach but be sure that use some declorinator (over several rinses) before you put the rock back in. There are tons of threads about them, just search the RC forums.